Heat Transfer Fluids

[wmconlon]

Perhaps the MW is not needed for the modeling in COFE, but the properties are apparently calculated in PCDManager on a molar basis using whatever curve fit one specifies. I have tabular properties and created correlations for them on a mass basis, but need to adjust the curve fits.

I think this is properly a ChemSep issue.

[jasper]

I reckon the same holds. If you specify 1000 gr/mol, then properties per kg are the same as properties per mole.

[wmconlon]

I wanted to come back to this topic, which I had abandoned as too complicated at the time, and I did the Heat Transfer Fluid (HTF) calculations outside of COFE/COCO.

A week ago I decided that I wanted to take another look and prepared temperature correlations for the HTF using the vendor's published property data for viscosity, thermal conductivity, density, specific heat and vapor pressure. After much back and forth, including extensive reading of the ChemSEP documentation, I realized that some temperature dependent properties need to be fitted on a molar basis.

So then I added the HTF as a property package, and found that configuring the HTF in PCDManager was not sufficient -- there was still a need to select property calculation methods in COFE. To get the liquid density curve fit I needed to treat it as a pure component.

But I ultimately ran aground with the enthalpy calculation. The EOS calculation of enthalpy was (unsurprisingly) inconsistent with the measured specific heat.

It seems to me that implementation of the HTF will require an external routine, like a thermo server or out of application process.

I don't know how complicated that is to do, but it seems to me something that we should ask vendors to provide.

For me, I will go back to performing my HTF calculations outside of COFE/COCO.

[jasper]

One option is to fit the ideal gas correlation to vapor enthalpy and then use the ideal enthalpy model for the vapor phase. Subtract vapor enthalpy from the liquid enthalpy and fit the heat of vaporization correlation to that. Then use the ideal liquid enthalpy model.

You will not have any pressure dependence in enthalpy this way.

Another option would indeed be to write an enthalpy calculation routine; TEA accepts this, but it requires some programming.